rotational mechanics?

Question

two forces F1 and F2 are acting horizontally on a spool at radius 2r and r respectively show that inorder to have zero friction force at the bottom the ratio F1/F2= ( I+2mr^2)/(4mr^2-I)
where I is the moment of inertia of spool and m is the mass.

Answer 1

Please provide clearer explanations.